[cathoderay57]

Since I am now seeking help here, maybe the Mods want to move the thread to Vintage Computers? I'll press on here for now. I have now got the parent computer that the Acbel API1PC36 comes from. It is a Power Mac G4. When connected to the motherboard, pressing the power switch just gives a twitch on the main fan then the thing stops. However, when run up on the bench with a 22R dummy load on the multi-plug relevant pins to defeat the 3.3v sense, and a jumper across another pair of pins, the PSU starts OK and keeps running, delivering the specified voltages. The "Badcaps" Forum suggests block replacement of electrolytic capacitors, which I am beginning to do. However, in Post #2 David mentioned a high value resistor connected to the rectified mains line sometimes goes high. I have struggled to find it. I cannot locate an exact circuit for this model, but the mains HT end and many other parts appear to be very similar to the one I have uploaded. R4 is only 0.04R and is OK. R3 is 10k but measures 4.9k in circuit. R67 is also 10k and similarly measures 4.9k in circuit. These are probably low because of other paths or devices in parallel - I didn't bother to des-solder them and re-test. The links from B+ go all over the place. It's a big ask, but please could David give me a clue as to which resistors I should be looking at? The only high-ish value I could find is R12 which checks out OK at 180k. Cheers, Jerry